In conventional filter cigarettes, the filter commonly consists of a single segment of filtration material, typically a continuous tow of filamentary cellulose acetate plasticised with triacetin, circumscribed by porous and/or non-porous plug wrap. The cellulose acetate is gathered together to form a rod which is cut to form individual filter segments. The filter for a smoking article may be made of one segment of filter rod, or may be made from multiple segments.
In the past it has been proposed to replace the continuous tow with randomly oriented discrete fibres of cellulose acetate. The advantages of using such kind of fibres have been reported and listed in several publications, like WO 2009/080368, WO 2009/093051, WO 2013/068337, WO 2013/164624 and WO 2013/164623. Filter manufacturing machines specifically developed for making such kind of filters are also known, e.g. Turmalin machine made by Hauni Maschinenbau AG, Germany.
With randomly oriented discrete fibres, filters having higher additive loadings can be produced compared to filters using continuous tow. In addition to this, the Turmalin machine is reported as allowing said higher loadings without using any plasticizer such as triacetin, e.g. in WO 2013/164624 and WO 2013/164623.
However, all publications are silent on how to process filters having said higher additive loading. Indeed, the present inventors have found that as soon as filters comprising randomly oriented discrete fibres and high additive loading are cut in order to form individual filter segments or to be assembled in multiple segments filters, a very significant amount of the additive is lost.
Therefore, there is a need to provide filters comprising randomly oriented discrete fibres and a stable, long lasting high additive loading with good performance of the additive, as well as smoking articles with these filters.